Splitable tip catheter with bioresorbable adhesive

ABSTRACT

Splitable-tip catheters are disclosed with bioresorbable adhesive to provide spatial separation of distal tip elements during use. The invention can be particularly useful in hemodialysis applications where it is desirable to separate blood extraction and return lumens. The adhesive facilitates insertion of the distal end of the catheter as an assembly, e.g., into a blood vessel using a single guidewire, while the bioresorbable nature of the adhesive allows the tip elements to separate in vivo.

FIELD OF THE INVENTION

The present invention generally relates to catheters and preferably tomulti-lumen catheters used for vascular access.

BACKGROUND OF THE INVENTION

Multi-lumen catheters and, in particular split-tip catheters, aredesirable for various treatment applications such as hemodialysis wherefluid extraction and infusion occur simultaneously. Hemodialysis is theseparation of metabolic waste products and water from the blood bydiffusion through a semipermeable membrane. Typically, a hemodialysisunit is connected to a patient's body by a catheter. The catheter'sdistal end is placed in a blood vessel and its proximal end is connectedto a hemodialysis unit.

During hemodialysis, a patient's blood flows through a double lumencatheter to the hemodialysis unit which provides filtration and controlsthe flow of blood. A double lumen catheter has two lumens thatindependently allow fluid extraction and return. For example, one lumencan be used for removing blood from a patient for processing in thehemodialysis machine and the other lumen can be used for subsequentlyreturning the processed blood back to the patient's circulatory system.

Parameters that can be varied to achieve adequate hemodialysis includeblood flow rate, dialysis solution flow rate, dialyzer competency, andtemperature. Generally, raising the blood flow rate increases dialyzerclearance of small molecular weight solutes. Consequently, higher bloodflow rates have been used to improve dialysis clearance efficiency.However, conditions such as access recirculation decrease clearance.Access recirculation is the recirculation of treated blood back into thehemodialysis unit causing inadequate dialysis. This problem effectivelyreduces blood flow rates thereby diminishing the efficiency of thehemodialysis process causing the duration of the treatment needed fordialysis to increase. Access recirculation can be particularly ofconcern when using a double lumen catheter due to the close proximity ofthe intake and outflow ports at the distal tip of the catheter.

Various double lumen catheter designs have been suggested for thepurpose of reducing access recirculation. The distal ends of intake andoutflow lumens have been longitudinally spaced 20-30 mm apart to preventrecirculation. For example, Twardowski et al. U.S. Pat. No. 5,569,182discloses that the lumen for return of blood back into the vein shouldterminate beyond the extraction lumen. The purpose of this is to preventcleansed blood, exiting from the outlet point of the catheter, fromre-entering the catheter's blood inlet point and returning to thedialysis machine. However, certain disadvantages have been noted by suchlarge longitudinal spacing between the distal ends of the respectivelumens. For example, blood flow stagnation in the region of the bloodvessel between two widely separated tips can lead to clot formation.

In addition to longitudinal spacing of the distal openings of the lumensfor blood extraction and return, others have suggested that the distalend of a multi-lumen catheter can be split such that the distal tips ofthe lumens can independently move in the blood vessel to optimize thefluid dynamics of the different functions (blood extraction and bloodreturn).

In general, good catheter outcomes depend on proper positioning of thecatheter in the blood vessel. Insertion complications includepneumothorax, hemothorax, and cardiac tamponade, as well as poor bloodflow rates, poor clearances, and long-term complications such ascatheter dysfunction and fibrin sheath formation. These complicationsare compounded by the use of double lumen catheters because of theirsize.

Additional difficulties can be encountered when split distal tips mustbe inserted into a blood vessel. Typical insertion techniques ofconventional double lumen catheters require the use of a peel-awaysheath over a guidewire. Frequently there is a preference to insert thecatheters without the use of a peel-away sheath to eliminate the risk ofan air embolism by the use of two guidewires, or alternatively,inserting the guidewire through the one lumen and threading it throughthe side hole channels of the other lumen thus utilizing one guidewire,referred to as the “weave technique”. Moreover, precise positioning of amulti-lumen catheter can be challenging because the exact placement ofthe tips cannot be assured. An improperly positioned multi-lumencatheter can further result in sub-optimal functionality requiringintervention.

Thus, there remains a need for a multi-lumen catheter that addresses theproblems of access recirculation yet retains the comparative ease ofinsertion of a single lumen catheter.

SUMMARY OF THE INVENTION

Splitable-tip catheters are disclosed having tip elements that arejoined with biodegradable or biosoluble adhesive to facilitate insertionand yet provide spatial separation of distal tip elements during use.The invention can be particularly useful in hemodialysis applicationswhere it is desirable to separate blood extraction and return lumens.The adhesive facilitates insertion of the distal end of the catheter asan assembly, e.g., into a blood vessel using a single guidewire, whilethe biodegradable or biosoluble nature of the adhesive allows the tipelements to separate in vivo. The term “bioresorbable” as used hereinencompasses both biodegradable and biosoluble materials.

The biodegradable adhesive, applied to the contacting surfaces of thedistal tips of the extraction and return lumens, can be formed fromvarious polymer or copolymer compositions. Additionally, the adhesivecan be composed such that the time in which the adhesive biodegrades orbiodisolves can be in the range of about 1 second to 1 hour. Moregenerally, the adhesives of the present invention can bio-resorb fromabout 1 second to about 7 days, or from about 1 second to about 1 day,or from about 1 second to about 1 hour, or from about 1 second to about10 minutes, or from about 10 seconds to about 5 minutes. In anotherembodiment a splitable tip catheter is disclosed having distal fluidopenings to accelerate dissolution. The biodegradable or biosolubleadhesive can be water soluble such that the introduction of saline orsimilar type fluid will dissolve the adhesive and facilitate theseparation of the distal tip elements.

An embodiment of the present invention provides a multi-lumen catheterdevice for hemodialysis having an elongate catheter body with at leastone blood extraction lumen and one blood return lumen extendinglongitudinally therethrough. The proximal end of the instrument can beadapted for coupling to a hemodialysis apparatus and the distal endterminates in separable distal tip portions adapted for insertion into ablood vessel. The distal end of the catheter includes a distalextraction tip portion for fluid coupling of the extraction lumen withthe blood vessel and a distal return tip portion for fluid coupling ofthe return lumen with the blood vessel, such that biodegradable orbiosoluble adhesive joins the distal tip portions together prior toinsertion into the blood vessel and facilitates the separation of thedistal tip portions from each other following insertion.

Another embodiment of the present invention provides a method forhemodialysis to include providing a multi-lumen catheter assembly withat least a blood extraction lumen and a blood return lumen extendinglongitudinally therethrough, each lumen having a proximal end adaptedfor coupling to a hemodialysis apparatus and a distal end terminating inseparable distal tip portions for blood extraction and return where thetip portions are joined together by a biodegradable or biosolubleadhesive. The method further provides for inserting the distal end ofthe catheter assembly into a blood vessel and allowing the adhesive todegrade such that the distal tip portions separate from each otherwithin the blood vessel.

Therefore, the present invention addresses current problems associatedwith conventional split-tip catheter insertion by joining the distaltips of a split-tip catheter with biodegradable or biosoluble adhesive.After insertion of the catheter into the patient, the biodegradable orbiosoluble adhesive dissolves and the distal tips of the split-tipcatheter are free to move and function like conventional split-tip,double lumen, triple lumen, or multi-lumen catheters.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a schematic, perspective view of an embodiment of the presentinvention showing distal tip portions joined together;

FIG. 1B is a schematic, perspective view of an embodiment of the presentinvention showing distal tip portions separated from one another;

FIG. 1C is a schematic view of an embodiment of the present invention inuse in the body of a patient;

FIG. 2A is a cross-section view of an embodiment of the presentinvention showing opposed “D” shaped lumens inside an outer sheath;

FIG. 2B is a cross-section view of an embodiment of the presentinvention showing unibody construction utilizing opposed “D” shapedlumens;

FIG. 2C is a cross-section view of an embodiment of the presentinvention showing yet another unibody construction;

FIG. 2D is a cross-section view of an embodiment of the presentinvention showing individual lumens inside an outer sheath;

FIG. 2E is a cross-section view of an embodiment of the presentinvention showing a unibody construction utilizing individual lumens;

FIG. 2F is a cross-section view of a variation of an embodiment of thepresent invention showing opposed “D” shaped lumens;

FIG. 2G is a cross-section view of an embodiment of the presentinvention showing three lumens;

FIG. 2H is a cross-section view of a variation of an embodiment of thepresent invention showing three lumens;

FIG. 2I is a cross-section view of a yet another variation of anembodiment of the present invention showing three lumens;

FIG. 3A is a schematic, perspective view of an embodiment of the presentinvention showing an adhesive application using spots of adhesive;

FIG. 3B is a schematic, perspective view of an embodiment of the presentinvention showing an adhesive application using regions of adhesive;

FIG. 4A is a cross-section view near the distal end of a catheteraccording to the present invention showing distal tip portions adheredto one another;

FIG. 4B is an distal cross-sectional view of another embodiment of thepresent invention showing alternative adhesive disposition;

FIG. 4C is a distal cross-sectional view of yet another adhesive design;

FIG. 5A is a schematic, perspective view of another embodiment of thepresent invention showing distal tip portions joined and wound about oneanother;

FIG. 5B is a schematic, perspective view of the embodiment in FIG. 5Awith the distal tip portions shown in a separated state;

FIG. 5C is a schematic, perspective view of an embodiment of the presentinvention showing one lumen wound about another lumen;

FIG. 6A is a schematic, perspective view of an embodiment of the presentinvention showing fluid openings in the distal tip portions;

FIG. 6B is a schematic, perspective view of an embodiment of the presentinvention showing a design having an additional center lumen;

FIG. 6C is a cross-sectional view of an embodiment of the presentinvention showing a design having an additional center lumen;

FIG. 7A is a schematic, perspective view of an embodiment of the presentinvention showing distal tip portions adhered to one another in a shapememory configuration;

FIG. 7B is a schematic, perspective view of the embodiment in FIG. 7Ashowing distal tip portions that are separated; and

FIG. 8 is schematic, perspective view of an embodiment of the presentinvention showing distal tip portions in an alternate shape memoryconfiguration.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term “bioresorbable” refers to materials that arebiodegradable or biosoluble such that they degrade or break down bymechanical degradation upon interaction with a physiological environmentinto components that are metabolizable or excretable over a period oftime.

The present invention includes various embodiments of a multi-lumencatheter for hemodialysis and methods of use. As shown in FIGS. 1A and1B, one embodiment of catheter 10 includes an elongate body 20 havingproximal and distal end 11 and 12, and at least one blood extractionlumen 30 and at least one blood return lumen 40 extending longitudinallytherethrough. Each lumen 30, 40 has a proximal end 30′, 40′ adapted todirect fluid to, or couple directly with, a hemodialysis apparatus (notshown), and a distal end 31,41 for insertion into a blood vessel. Distalextraction and return tip portions 32, 42 of each lumen 30, 40 include adistal end opening 33, 43 formed therein to provide for simultaneousflow of blood in opposite directions during hemodialysis. The distalextraction and return tip portions 32, 42 are joined by bioresorbableadhesive 90 prior to being inserted into a blood vessel such that afterinsertion, the bioresorbable adhesive degrades sufficiently to allow thedistal extraction and return tip portions of each lumen 30, 40 toseparate from one another.

FIGS. 1A and 1B illustrate an outer sheath 50 which covers and enclosesthe lumens 30, 40. The outer sheath 50 can be any shape and size and canbe made of the same material as the lumens 30, 40 or other materialcompatible with insertion into a blood vessel. As illustrated in theembodiment shown in FIGS. 1A and 1B, the outer sheath 50 terminatesproximal to the distal ends 31, 41 of the lumens 30, 40 such that thedistal extraction and return tip portions 32, 42 of each lumen canseparate from one another after being inserted into a blood vessel. FIG.2A shows a cross-section 2-2 of one embodiment of an outer sheath 50.The outer sheath 50 can be any thickness and can have varying inner andouter shapes as well as varying inner and outer dimensions.

FIG. 2B illustrates another embodiment showing a cross-section of anelongate body 20 having unibody construction 500 which incorporates theblood extraction and blood return lumens 308, 408 in a single elongatebody 20. The unibody catheter can be constructed such that sheathmaterial 500′ separates the lumens 308, 408. The amount of sheathmaterial around each lumen 308, 408 and in-between each lumen can varybut preferably allows for blood extraction and blood return inaccordance with hemodialysis. Separating the sheath material in-betweenboth lumens 308, 408 along a vertical axis y at one end of the unibodyconstruction can separate the lumens from one another into distinctdistal portions. A variety of methods known to one skilled in the artcan be used to separate the material such as for example cutting orscoring.

In another embodiment of the present invention the elongate body 20 canbe formed such that the blood extraction and blood return lumens 30 and40 (or 300 and 400) are non-circular to increase the areas of theirouter surfaces 350, 450 that are in contact as shown, for example, incross-section in FIGS. 4A and 6C. As shown in FIGS. 3A and 3B, thefacing surfaces can be joined by spots 91 as well as regions 94 ofadhesive (further described below). The configuration of the lumens inthis embodiment allows the lumens, as joined, to resemble a single,circular lumen prior to insertion. After insertion of the distalextraction and return tip portions (e.g., tip portions 32 and 42 or tipportions 325 and 425), into a blood vessel, the bioresorbable adhesive90 can dissolve allowing the tip portions to separate and facilitatehemodialysis.

The lumens 30, 40 can have a variety of cross-sectional shapes and sizesbut preferably, as shown in the embodiments in FIGS. 1B, 2A, 2B, 2F, 3A,3B, 4A, 4C, 6B, 6C, 7A, and 7B, the lumens are “D” shaped. Alternately,each of the lumens 30, 40 can have a cross-sectional shape, size, orarea that can be distinct from the other, as shown, for example, inFIGS. 2C, 2G, and 2H. FIG. 2A is a cross-section view of an embodimentof the present invention showing opposed “D” shaped lumens inside anouter sheath. FIG. 2B is a cross-section view of an embodiment of thepresent invention showing unibody construction utilizing opposed “D”shaped lumens. FIG. 2C is a cross-section view of an embodiment of thepresent invention showing yet another unibody construction. FIG. 2D is across-section view of an embodiment of the present invention showingindividual lumens inside an outer sheath. FIG. 2E is a cross-sectionview of an embodiment of the present invention showing a unibodyconstruction utilizing individual lumens. FIG. 2F is a cross-sectionview of a variation of an embodiment of the present invention showingopposed “D” shaped lumens. FIG. 2G is a cross-section view of anembodiment of the present invention showing three lumens. FIG. 2H is across-section view of a variation of an embodiment of the presentinvention showing three lumens. FIG. 2I is a cross-section view of a yetanother variation of an embodiment of the present invention showingthree lumens. The lumens 30, 40 can be made of any material consistentwith materials presently known for catheters including any materialwhich allows the distal tip portions 32, 42 of the lumens to be flexibleand facilitate hemodialysis.

The distal extraction and return tip portions 32, 42 of each lumen 30,40 include distal end openings 33, 43 formed thereon for the extractionor return of blood or other bodily fluids. The openings are preferablysized to allow the carrying of blood to and from the hemodialysis unit.The distal extraction and return tip portions 32, 42 can be the samelength or, as shown in FIGS. 1A and 1B, can be different lengths. Asshown, the distal extraction tip portion 32 of the blood extractionlumen 30 terminates proximal to the distal return tip portion 42 of theblood return lumen 40. However, in another embodiment, the distal returntip portion 42 of the blood return lumen 40 can terminate proximal tothe distal extraction tip portion 32 of the blood extraction lumen 30.The longitudinal distance d between the distal extraction and return tipportions 32, 42 of each lumen 30, 40 can vary but preferably allows forperforming blood extraction and blood return in accordance withhemodialysis. Prior to the distal end 11 of the catheter being insertedinto a blood vessel, the distal extraction and return tip portions 32,42 of the lumens 30, 40 are joined to one another with bioresorbableadhesive 90. After insertion into the blood vessel, bioresorbableadhesive 90 facilitates the separation of the distal extraction andreturn tip portions 32, 42 of the lumens 30, 40. The bioresorbableadhesive may degrade in blood in a desired time period, such as, forexample, about 1 second to about 7 days, about 1 second to about 1 day,or about 1 second to about 1 hour.

The bioresorbable adhesive 90 used to join the distal extraction andreturn tip portions, 32, 42 of the lumens 30, 40 to one another can be acomposition selected from the group of polymers consisting ofpolylactides, polyglycolides, polylactones, polyorthoesters,polyanhydrides, and copolymers and combinations thereof. In general,bioresorbable adhesives have bonding elements and degradable elements.The degradable elements can have the components of polylactide,polyglycolide and polylactones (polycaprolactone). The bonding elementscan have hydrogen bonding strength (polyvinyl alcohol, polysaccharides)or can be able to polymerize as a single component (cyanoacrylates) oras two components (epoxy compound plus amino compounds, or radical(light) initiators of acrylate compounds).

Proteins, sugars, and starch can also be used as an adhesive. By way ofnon-limiting example, antithrombotic agents such as heparin and hirudin,citrate, antithrombinheparin complex, and albumin heparin complex aswell as anti-infective agents such as chlorohexidine, silver,antibiotics, and antiseptic agents may be added to the adhesive.

In an embodiment of the present invention, polymers which can be usefulinclude polyurethane, generally described as a copolymer of polyethyleneglycol with polylactide or polyglycolide end capped with methacrylates.Another embodiment can include a two component composition, onecomponent preferably including a low molecular weight polyurethane endcapped with methacrylates, and the other component preferably includingpolylactide, polyglycolide, or polycaprolactone end capped withmethacrylate.

In another embodiment of the present invention, one or more componentscan be used from styrene, methyl methacrylate, methyl acrylate, ethylenedimethacrylate, ethylene diacrylate, acrylamide, diurethanedimethacrylate, polyisoprenegraft-maleic acid monomethyl ester,azobis(cyanovaleric acid), azobiscyclohexanecarbonitrile,azobisisobutyronitrile, benzoyl peroxide, iron(II) sulfate, polyvinylalcohol, dextran, polysaccharide, epichlorohydrin, ethylenediamine,diaminocyclohexane, diamino propane, copolymers with polylactide andpolyethylene oxide as the blocks and acrylate, methacrylate as the endgroups, cyanoacrylates, ethyl-2cyanoacrylate, propyl-2-cyanoacrylates,pentyl-2-cyanoacrylate, hexyl-2-cyanoacrylate, andoctyl-2-cyanoacrylate, ammonium persulfate and/or polyethylene glycolmethacrylate when water, organic solvent such as dichloromethane,chloroform, tetrahydrofuran, acetone, petroleum ether, acetyl acetate,dimethylformamide, or the mixture thereof, is combined with theaforementioned solvents.

As shown in FIGS. 1A, 3A, and 3B, bioresorbable adhesive can be appliedalong a facing surface 35, 45 of either, or both, distal extraction andreturn tip portions 32, 42 of the lumens 30, 40 to facilitate thejoining of the lumens along their longitudinal length l prior toinsertion of the distal end 11 of the catheter 10 into a blood vessel.(As used throughout, “catheter 10” refers to the various embodiments ofthe present invention.) FIG. 1A shows bioresorbable adhesive 90 appliedalong a longitudinal length l of the distal extraction and return tipportions 32, 42 of each lumen 30, 40. However, the bioresorbableadhesive 90 need not be applied along the entire length l of the facingsurfaces 35, 45 of each lumen 30, 40 but is preferably applied such thatthe adhesive facilitates the joining of the distal extraction and returntip portions 32, 42 of the lumens 30, 40 prior to insertion into a bloodvessel and allows the distal extraction and return tip portions of thelumens to separate after insertion.

In the embodiments described herein, the bioresorbable adhesive 90preferably dissolves after insertion into a blood vessel to provideseparation of the distal extraction and return tip portions 32, 42 ofthe lumens 30, 40 in a time period ranging from 1 minute to 1 hour. Thisrange can be controlled by using different compositions of thebioresorbable adhesive 90 as well as by the amount of adhesive appliedto join the distal extraction and return tip portions 32, 42 of thelumens 30, 40 together. In another embodiment with opposed distal fluidopenings 80 (further described below), the bioresorbable adhesive 90 canbe water soluble such that the introduction of saline or similar typefluid will effectuate the separation of the distal extraction and returntip portions 32, 42 of the lumens 30, 40. In this instance, the adhesivewill not dissolve until a time after the introduction of the solublesolution into the lumens 30, 40.

As shown in another embodiment in FIG. 3A, the bioresorbable adhesivecan also be applied to the facing surfaces of the distal extraction andreturn tip portions 32, 42 of the lumens 30, 40 in form as discretespots 91. The spots 91 of bioresorbable adhesive 90 can be appliedcontinuously along the entire longitudinal length l of the distalextraction and return tip portions 32, 42 of the lumens 30, 40 orselectively in an assortment of areas thereof. Preferably, thebioresorbable adhesive 90 is applied such that the spots 91 of adhesivefacilitate the joining of the distal extraction and return tip portions32, 42 of the lumens 30, 40 prior to insertion into a blood vessel andallow the distal extraction and return tip portions of the lumens toseparate after insertion. The spots 91 of bioresorbable adhesive 90 canvary in number and size in order to facilitate the joining of the tipportions of the lumens.

FIG. 3B shows yet another embodiment of the application of thebioresorbable adhesive 90 in the form of discrete regions 94. Discreteregions 94, like the spots 91 stated above, of bioresorbable adhesive 90can be applied to the facing surfaces of the distal extraction andreturn tip portions 32, 42 of the lumens 30, 40. The discrete regions 94of bioresorbable adhesive 90 can also be different lengths and can beapplied in addition to discrete spots 91 of adhesive such that theadhesive facilitates the joining of the distal extraction and return tipportions 32, 42 of the lumens 30, 40 prior to insertion into a bloodvessel and allows the distal extraction and return tip portions of thelumens to separate after insertion.

FIGS. 4A-4C show cross-sections of the distal extraction and return tipportions 32, 42 of the lumens 30, 40 detailing alternate embodiments ofthe bioresorbable adhesive 90 application. FIG. 4A shows bioresorbableadhesive 90 applied at the contact point 70 of the facing surfaces 350,450 of the lumens 30, 40. FIG. 4B shows another embodiment of anapplication of the bioresorbable adhesive 90 such that the adhesive, asapplied, joins non-contacting surfaces 36, 46 of the distal extractionand return tip portions 32, 42 of the lumens 30, 40. FIG. 4C shows avariation on the embodiment shown in FIG. 4A where the bioresorbableadhesive 90 surrounds the distal extraction and return tip portions 32,42 of the lumens 30, 40 forming a continuous cross-section of adhesivecoating notwithstanding the distal extraction and return tip portions ofthe lumens extending therethrough. As stated above, the bioresorbableadhesive 90 need not be applied along the entire length of the distalextraction and return tip portions 32, 42 of each lumen 30, 40 but ispreferably applied such that the adhesive facilitates the joining of thedistal extraction and return tip portions of the blood extraction andblood return lumens prior to insertion into a blood vessel and allowsthe distal extraction and return tip portions of the lumens to separateafter insertion. It should be noted that because the lumens 30, 40 canbe various shapes, as stated above, the bioresorbable adhesive 90 neednot be applied to all of the contact area along length l of the facingsurfaces 35, 45 of each lumen 30, 40, as shown in FIG. 1A. As shown inFIGS. 3A and 3B, the bioresorbable adhesive 90 can be applied as aregion 94, spot 91, or other shape, to a section of the contact area andneed only be applied to facilitate the joining function.

FIG. 5A illustrates another embodiment of the present invention. Asshown, the lumens 30, 40 are twisted about, or otherwise wrapped, aroundone another. The wrapped lumens can be twisted about one another suchthat there are non-contact areas, along the longitudinal length l of thedistal extraction and return tip portions of each lumen 30, 40 as shownin FIG. 5A. In FIG. 5B, the distal tip elements are shown in a separatedstate. The distal extraction and return tip portions of each lumen 30,40 can wrap around one another any number of times, as well as wrap suchthat one lumen 30 is wound around the other lumen 40 as shown in FIG.5C, or vice versa. In FIG. 5A, bioresorbable adhesive 90 can be appliedwhere the distal extraction and return tip portions of the lumens 30, 40contact one another. As stated above, the bioresorbable adhesive 90 canbe applied in discrete spots or regions where the distal extraction andreturn tip portion surfaces contact one another. However, thebioresorbable adhesive need not be applied to all contact points of thetwisted lumens 30, 40 so long as the joining of the distal extractionand return tip portions of the lumens 30, 40 can be facilitated. Thevarious compositions and methods of application of the bioresorbableadhesive 90 application previously described above can also be used withthe twisted embodiment catheter design as well.

In another embodiment of the present invention, FIG. 6A shows distalfluid openings 80, in formed in the distal extraction tip portion 32 oflumen 30. It should be understood from the drawings that in theembodiment shown, the distal fluid openings 80 can either be in additionto, or in place of, the distal end opening 33 located on the distalextraction tip portion 32 of lumen 30. The distal fluid openings 80 canbe any shape and size and can be located in a variety of places on lumen30 as illustrated. However, FIG. 6A shows the distal fluid openings 80located on facing (contacting) surface 35 of the distal extraction tipportion 32 of lumen 30. In this embodiment, the distal fluid openings 80can be filled or covered with fluid activated bioresorbable adhesive 900and joined to lumen 40 along its facing surface 45. After insertion ofthe catheter into a blood vessel, saline or similar type fluid can beintroduced into lumen 30 at its proximal end 30′ such that the fluidtravels through the lumen to the distal fluid openings 80 and dissolvesthe fluid activated bioresorbable adhesive 900 thereby separating thedistal extraction and return tip portions 32, 42 along theirlongitudinal length/to facilitate hemodialysis. Bioresorbable adhesive90 can also be applied to the contact surfaces 35, 45 of each lumen aspreviously described above in addition to the distal fluid openings 80being filled or covered with fluid activated bioresorbable adhesive 900.

FIG. 6B shows yet another embodiment in which the catheter 10 can bedesigned to facilitate separation of its distal tips 325,425 afterinsertion into a blood vessel. Catheter 10 can include a center lumen 60extending in-between lumens 300, 400 from a proximal end 120 to aseparation point 62 and can be used to carry saline or a similar typefluid. At the separation point 62, the center lumen splits into twocenter lumen halves 63′, 64′ each half located in a facing surface 350,450 of each lumen 300, 400. The center lumen 60 can be made of a varietyof cross-sectional shapes but is preferably circular. As shown, thecenter lumen halves 63′, 64′ terminate proximal to the distal ends 310,410 of lumens 300, 400. It should be noted that a mirrored portion ofcenter lumen half 64′ is located in the facing surface 450 of distalreturn tip 425. The proximal end of center lumen 60, which is out ofview in FIG. 6B, can extend at the proximal end 120 of catheter 10anywhere outside the patient so long as the center lumen 60 can beaccessible for saline fluid introduction. As shown in FIG. 6C, thecenter lumen 60 and the center lumen halves 63′, 64′ are not in fluidcommunication with either of the lumens 300, 400. Distal extraction andreturn tip portions 325, 425 can have fluid activated bioresorbableadhesive 900 applied anywhere within center lumen halves 63′, 64′ distalof a center lumen gap. The adhesive 900 can also be applied at or beyonda center lumen half end, to facilitate separation of the distal tipportions 325, 425. The center lumen gap, of any desirable length, shouldremain free of fluid activated bioresorbable adhesive 900 and in fluidcommunication with a blood vessel in order to allow any extraneoussaline or similar type fluid to be displaced between the facing surfaces350, 450 and into the bloodstream during the dissolving process.

In this embodiment, the catheter 10 is inserted into a patient andsaline or other type fluid can be introduced into the center lumen 60 atits proximal end which dissolves the fluid activated bioresorbableadhesive 900 applied at or beyond center lumen gap. Once separated, thedistal tip portions 325, 425 can facilitate blood extraction and bloodreturn in accordance with hemodialysis through distal end openings oflumens 300, 400.

In FIGS. 7 A and 7B, another embodiment of the present invention isshown in which one or both of the lumens 30, 40 can be made of a shapememory material such that after insertion of the distal end 11 of thedevice into a blood vessel, and upon the bioresorbable adhesive 90dissolving, the lumens, and more preferably the distal extraction andreturn tip portions 32, 42 thereof, can separate to a pre-adhesiveposition. The distal extraction and return tip portions 32, 42 of thelumens 30, 40 can be made of polymer material or other material asneeded or combined to facilitate the shape memory in the describedembodiment. FIGS. 7 A and 7B illustrate the lumens 30, 40 in thisconfiguration. The distal extraction and return tip portions 32, 42 ofeach lumen 30, 40 are joined with bioresorbable adhesive 90 prior toinsertion into a blood vessel. A memory gap 93 can be located betweenthe lumens and distal of the outer sheath 50. The memory gap can be anylength and width but preferably allows for a configuration such that thelumens 30, 40 are not pinched after joining As shown, each lumen 30, 40exits the outer sheath 50 in a non-parallel, diverging direction. Therelative angle a at which the lumens 30, 40 exit the outer sheath 50 canvary. Bioresorbable adhesive 90 can be applied, in any manner describedherein, to join the lumens 30, 40 distal of the memory gap 93. FIG. 7Bshows the lumens 30, 40 in roughly a “pre-adhesive” configuration aswell as in an “after insertion into a blood vessel” configuration. Itshould be noted that the lumens 30, 40 illustrated in FIG. 7B, canseparate more or less, after being inserted into a blood vessel, ascompared to their pre-adhesive state.

In another embodiment, the distal extraction and return tip portions 32,42 of each of the lumens 30, 40 can be preformed to exit the outersheath 50 in a substantially parallel direction and then angularlydiverge from one another, at a location distal from the outer sheath,upon the degradation of the bioresorbable adhesive 90, as shown in FIG.8. The distal extraction and return tip portions 32, 42 of each lumen30, 40 shown in FIG. 8, exit the outer sheath 50 in a distal directionand are substantially parallel relative to one another. As thebioresorbable adhesive 90, applied in any manner described herein,dissolves, the distal extraction and return tip portions 32, 42 of thelumens 30, 40 substantially separate and angularly diverge from oneanother along a longitudinal axis b. Distal extraction and return tipportions 32,42 of each lumen 30,40 can be pre-formed from polymer orsimilar type polymer materials to effectuate this divergence. As furthershown in FIG. 7, the distal extraction and return tip portions 32, 42can re-converge toward each other if desired or can continue divergingas shown in FIG. 6B.

In use, a catheter 10 is provided having distal extraction and returntip portions 32, 42 which are joined to one another using any of thebioresorbable adhesive applications described throughout thisspecification. The proximal end 12 of the catheter 10 can be attached toa hemodialysis apparatus using various attachment means known to oneskilled in the art. The distal end 11 of the catheter 10 can be insertedinto a blood vessel wherein the bioresorbable adhesive 90 is allowed todissolve in a time in the range of 1 minute to 1 hour, such that thedistal extraction and return tip portions 32, 42 of the blood extractionlumen 30 and the blood return lumen 40 separate from each other withinthe blood vessel. Blood extraction and blood return can be subsequentlycommenced through each lumen 30, 40 according to hemodialysis methodsand practices.

Accordingly, the embodiments of the present invention are not limited bywhat has been particularly shown and described, except as indicated bythe appended claims. All publications and references cited herein areexpressly incorporated herein by reference in their entirety.

What is claimed is:
 1. A method for hemodialysis, comprising: providinga multi-lumen catheter assembly with at least a blood extraction lumenand a blood return lumen extending longitudinally therethrough, having aproximal end adapted for coupling to a hemodialysis apparatus, andhaving a distal end terminating in separable distal tip portions forblood extraction and return, the tip portions joined together by abioresorbable adhesive including a bonding element and a degradableelement, at least a portion of the bioresorbable adhesive disposedbetween the tip portions; inserting the distal end of the catheterassembly into a blood vessel; and allowing the bioresorbable adhesive todegrade such that the distal tip portions separate from each otherwithin the blood vessel.
 2. The method according to claim 1, wherein theextraction and return lumens are independent of each other to providesimultaneous flow of blood in opposite directions during hemodialysis.3. The method according to claim 1, wherein the adhesive comprises ahydrophilic polymer.
 4. The method according to claim 1, wherein theadhesive degrades in blood to provide separation of the distal tipportions from each other in less than a hour.
 5. The method according toclaim 1, wherein the adhesive degrades in blood in a time period rangingfrom about 1 second to about 1 day.
 6. The device according to claim 1,wherein the adhesive comprises a protein, a sugar, and a starch.
 7. Thedevice according to claim 1, wherein the adhesive comprises anantithrombotic, anti-septic, or anti-stenotic agent.
 8. The methodaccording to claim 1, wherein the distal tip portions are flexible. 9.The method according to claim 1, wherein the distal tip portions are ofdifferent lengths.
 10. The method according to claim 1, wherein theextraction and return lumens have different cross-sectional areas. 11.The method according to claim 1, wherein at least one of the distal tipportions has a plurality of openings for fluid flow.
 12. The methodaccording to claim 1, wherein the elongate catheter body has unibodyconstruction with the extraction lumen and the return lumen incorporatedtherein.
 13. The method according to claim 1, wherein extraction andreturn lumens are separate tubular elements and partially joined by anouter sheath.
 14. The method according to claim 1, wherein the adhesivecovers at least a portion of the outer surface of each distal tipportion.
 15. The method according to claim 1, wherein the adhesiveapplied to the surface of each distal tip portion forms a continuouslinear bond.
 16. The method according to claim 1, wherein the adhesiveapplied to the surface of each distal tip portion forms discrete spots.17. The method according to claim 1, wherein at least one distal tipportion comprises a shape memory material.
 18. The method according toclaim 1, wherein at least one distal tip portion is coiled about anothertip portion.
 19. The method according to claim 1, wherein the cathetercontains an additional lumen for fluid administration or sampling.
 20. Amethod for hemodialysis, comprising: providing a multi-lumen catheterassembly with at least a blood extraction lumen and a blood return lumenextending longitudinally therethrough, having a proximal end adapted forcoupling to a hemodialysis apparatus, and having a distal endterminating in separable distal tip portions for blood extraction andreturn, a memory gap formed between the extraction lumen and the returnlumen, the tip portions joined together by a bioresorbable adhesiveincluding a bonding element and a degradable element; inserting thedistal end of the catheter assembly into a blood vessel; and allowingthe adhesive to degrade such that the distal tip portions separate fromeach other within the blood vessel; and wherein the memory gapfacilitates the separation of the distal tip portions from each other toa pre-adhesive position following degradation of the adhesive.